This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. To explore the mechanisms for hypoglycemia in insulin-secreting tumors. Our hypothesis is that hypoglycemia is caused not only be excess insulin secretion, but also by abnormalities in regulatory mechanisms. The major regulatory mechanism we will study are suppression of insulin secretion;hormonal and fuel counterregulation;and oscillatory insulin secretion.